#folder {
    width: 400px;
    height: 500px;
    margin: 0 auto;
    background: url("./img/folder.png") center no-repeat;
    /*图片占容器80%*/
    background-size: 80%;
}

/*动态绑定的css样式,当ended为true时这里的样式将生效*/
#folder.burst{
    background-image: url("./img/folder_broken.png");
}

#progress-bar{
    width:200px;
    border: 2px black solid;
    margin: 0 auto 20px auto;
}

#progress-bar div{
    height: 20px;
    background-color: crimson;
}

#controls{
    width: 160px;
    margin: 0 auto;
}

#controls button{
    margin-left: 20px;
}